# Linked Questions

19 questions linked to/from On a trick to derive the Noether current
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### Why can't any term which is added to the Lagrangian be written as a total derivative (or divergence)?

All right, I know there must be an elementary proof of this, but I am not sure why I never came across it before. Adding a total time derivative to the Lagrangian (or a 4D divergence of some 4 ...
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### What is the meaning of the parameter in Noether's theorem?

According to the explanation of Noether's theorem in Peskin & Schroeder's QFT book, pp. 17-18, If the Lagrangian $\mathcal{L}(x)$ change to \mathcal{L}(x)+\alpha\partial_\mu\mathcal{J}^\mu\tag{...
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### Global and local symmetries in Noether's theorem. And also Stress-Energy tensors

Noether's theorem for fields is usually given as follows: Given a field theory with action $S=\int\mathcal{L}(\phi,\partial\phi)d^4x$, and given a one-parameter variation of the fields $\phi_\epsilon$...
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### Noether's theorem under arbitrary coordinate transformation

Noether's theorem states that every differentiable symmetry of the action of a physical system has a corresponding conservation law. Suppose our action is of the form \$S = \int d^4x\, \mathcal{L}(\...

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